The field of the invention relates generally to the measurement of air gaps between proximity sensors and related metal targets, and more specifically to a proximity sensor interface device for verifying the correct air gap between a proximity sensor and a metal target.
In one application, proximity sensors for pressurized access doors are difficult to mechanically test due to limited space constraints both within the small confines of the sensor installation itself and the general area where the access door is located. Proper rigging (mechanical placement) of the proximity sensors is critical to provide a true indication of the access door's latched (or unlatched) condition. When the proximity sensors are not properly located in such an application, one result may be a false indication during a flight. While such nuisance indications are not necessarily a safety-of-flight issue, they may be cause for unnecessary aborted flights.
Currently, there are three solutions that are utilized to ensure proper mechanical placement of proximity sensors in the access door application. In the first solution, the access doors are mechanically rigged either at pre-integration or final assembly and delivery mechanically using modified bent-up feeler gauges. However, limited space constraints make it virtually impossible to mechanically rig the proximity sensors. More specifically, due to the relatively tight space inside the sensor installation, it is difficult to get hard feeler gauges into the space to successfully measure the gap between the proximity sensor and its target mechanism. Moreover, the modified bent-up gauges currently utilized are not accurate and difficult to insert into the air gap. Clay or metrological rubber is also difficult to apply because the access door sensor application is a sliding joint. As a result, capturing the true air gap in a modeling medium is also not very accurate.
The second solution is an internal proximity sensor rigging aid, which is a tool available on maintenance laptop computers which provides the capability to electronically rig the proximity sensors. This device and program utilize the aircraft's on-board proximity sensor data concentrator and general processing modules to drive/interrogate the sensors in exactly the same way as in actual ground operation/flight. However, this solution assumes that power is available on the aircraft. In most access door rigging manufacturing sequences, the doors are installed and the proximity sensors are rigged at pre-integration sites. As such, systems and aircraft power may not necessarily be available.
Another device is known that electronically rigs the proximity sensors. However, this device is a relatively large unit and so placement of the device conveniently within the confined aircraft space to test the proximity sensor mechanical is questionable. More specifically, this proximity sensor device requires a reference inductor in order to determine the air gap between a proximity sensor face and an associated target mechanism.